It is a distinctive feature of rotary lobe pumps that they provide a particularly gentle positive fluid transfer. Moreover, their pumping chamber is easily accessible and can be effectively cleaned upon removal of the rotor. For the above-mentioned reasons, rotary lobe pumps meet very stringent hygiene standards and are preferred in food production applications, pharmaceutical processes and biotechnology.
On known rotary lobe pumps, the rotors can be pulled off the drive shaft ends, projecting into the pumping chamber, once the front housing wall has been removed. In order to ensure an accurate positioning of the rotor in the direction of rotation, the drive shaft ends are provided with a gear rim. The retention of the rotor against axial displacement on the drive shaft is achieved outside the pumping chamber in rotary lobe pumps of known design. For this purpose, a sleeve attached to the rotor is passed through the sealing hub in such a manner that a bead-shaped edge of this sleeve presses against a corresponding ring surrounding the drive shaft outside the pumping chamber. The bead-shaped edge and the ring are secured relative to each other by means of a detachable clamp.
One disadvantage of the prior retention system lies in the fact that the removal, and particularly the installation of the clamp, is a highly complex and time-consuming process. Thus, a tool is necessary to loosen the bolts and to remove the clamp, which itself comprises two half-shells enclosing the shaft and the sleeve. To provide adequate handling access to the clamps, these must be surrounded by a sufficient clearance. The distance between the pumping chamber and the housing of the coupling must be large enough to accommodate a fitter's hand. As the clamp is so awkward to handle, maintenance and cleaning work on the pump is fairly complicated and inconvenient to perform.